History and Diversity of Life I Origin of

History and Diversity of Life I. Origin of Life Hypotheses

4. 5 bya: Earth Forms A. The Early Earth and Earth History Graviational sorting of materials…heavy to the core, gases released under pressure…

A. The Early Earth and Earth History - Earliest Atmosphere - probably of volcanic origin Gases produced were probably similar to those released by modern volcanoes (H 2 O, CO 2, SO 2, CO, S 2, Cl 2, N 2, H 2) and NH 3 and CH 4

4. 0 bya: Oldest Rocks 4. 5 bya: Earth Forms A. The Early Earth and Earth History

4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History Stromatolites - communities of layered 'bacteria'

4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History Putative microfossil bacteria from Australia that date to 3. 4 by

2. 3 -2. 0 bya: Oxygen in Atmosphere 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

0. 5 bya: Cambrian 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 065 bya: Cenozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 065 bya: Cenozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms A. The Early Earth and Earth History 4. 5 million to present (1/1000 th of earth history)

B. The Formation of Biologically Important Molecules - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously Aleksandr Oparin (1894 -1980) J. B. S. Haldane (1892 -1964)

B. The Formation of Biologically Important Molecules - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously - Miller-Urey (1953) all biologically important monomers have been produced by these experiments, even while changing gas composition and energy sources

C. Acquiring the Characteristics of Life Three Primary Attributes: - Barrier (phospholipid membrane) - Metabolism (reaction pathways) - Genetic System

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane - form spontaneously in aqueous solutions

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane 2. Metabolic Pathways 3. Evolution of a Genetic System - conundrum. . . which came first, DNA or the proteins they encode? DNA RNA (m, r, t) protein

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane 2. Metabolic Pathways 3. Evolution of a Genetic System - conundrum. . . which came first, DNA or the proteins they encode? DNA stores info, but proteins are the metabolic catalysts. . . RNA (m, r, t) protein

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane 2. Metabolic Pathways 3. Evolution of a Genetic System - conundrum. . . which came first, DNA or the proteins they encode? - Ribozymes info storage AND cataylic ability

C. Acquiring the Characteristics of Life 1. Evolution of a Membrane 2. Metabolic Pathways 3. Evolution of a Genetic System - conundrum. . . which came first, DNA or the proteins they encode? - Ribozymes - Self replicating molecules - three stage hypothesis

Stage 1: Self-replicating RNA evolves RNA

Stage 1: Self-replicating RNA evolves RNA m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 2: RNA molecules interact to produce proteins. . . if these proteins assist replication (enzymes), then THIS RNA will have a selective (replication/reproductive) advantage. . . chemical selection.

DNA Reverse transcriptases m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

Can this happen? Are their organisms that read RNA and make DNA?

Can this happen? Are their organisms that read RNA and make DNA? yes - retroviruses. .

DNA m- , r- , and t- RNA Already have enzymes that can make RNA. . . PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

DNA m- , r- , and t- RNA Already have enzymes that can make RNA. . . PROTEINS (REPLICATION ENZYMES) Stage 3: Mutations create new proteins that read RNA and make DNA; existing replication enzymes replicate the DNA and transcribe RNA.

DNA This is adaptive because the two-step process is more productive, and DNA is more stable (less prone to mutation). m- , r- , and t- RNA PROTEINS (REPLICATION ENZYMES) Stage 4: Mutations create new proteins that replicate the DNA instead of replicating the RNA. . .

DNA m- , r- , and t- RNA This is adaptive because the two-step process is more productive, and DNA is more stable (less prone to mutation). And that's the system we have today. . PROTEINS (REPLICATION ENZYMES) Stage 4: Mutations create new proteins that replicate the DNA instead of replicating the RNA. . .

D. Summary: STEPS REQUIRED FOR THE SPONTANEOUS, NATURAL FORMATION OF LIFE, and the evidence to date: 1. Spontaneous synthesis of biomolecules - strong evidence; Miller. Urey experiments. 2. Polymerization of monomers into polymers (proteins, RNA, sugars, fats, etc. ) - strong evidence; Fox and Cairns-Smith experiments. 3. Formation of membranes - strong evidence; behavior of phospholipids in solution. 4. Evolution of metabolic systems - reasonable hypotheses, and genetic similarity in genes involved in particular pathways (suggesting gene duplication and subsequent evolution of new genes and elaboration of existing pathways) 5. Evolution of a genetic system - a reasonable hypothesis and significant corroborating evidence that it could happen. But no experimental evidence of the process evolving through all three steps. 6. How did these three elements (membrane, metabolism, genetic system come together? ) a few untested hypotheses.

Diversity I. Origin of Life II. A Brief History of Life

The Diversity of Life I. A Brief History of Life 2. 3 -2. 0 bya: Oxygen 2. 0 bya: first eukaryotes 3. 5 bya: Oldest Fossils 4. 0 bya: Oldest Rocks 4. 5 bya: Earth Forms A. Introduction B. Timeline Grypania spiralis – possibly a multicellular algae, dating from 2. 0 by

The Diversity of Life I. A Brief History of Life A. Introduction B. Timeline - Life was exclusively bacterial for ~40% of life’s 3. 5 by history - Ecosystems evolved with bacterial producers, consumers, and decomposers. - Multicellular eukaryotic organisms evolved that use and depend on these bacteria

For ~40% of life’s history, life was exclusively bacterial 0. 7 bya: first animals 0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 065 bya: Cenozoic 2. 3 -2. 0 bya: Oxygen 2. 0 bya: first eukaryotes 3. 5 bya: Oldest Fossils 4. 0 bya: Oldest Rocks 4. 5 bya: Earth Forms The Diversity of Life I. A Brief History of Life A. Introduction B. Timeline

Ecological Roles Played By Prokaryotes ATMOSPHERE N fixation Photosynthesis BIOSPHERE Absorption LITHOSPHERE Respiration Energy harvest of animals and plants Decomposition

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System - a ‘nested’ hierarchy based on morphology

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics Evolution explained this nested pattern as a consequence of descent from common ancestors. Modern biologists view the classification system as a means of showing the phylogenetic relationships among groups

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. OLD NEW HOMINIDAE PONGIDAE Genera: Australopithecus Homo Genera: Pan Gorilla Pongo

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. OLD Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Class: Mammalia Class: Aves

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics NEW

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. OLD

The Diversity of Life I. A Brief History of Life II. Classifying Life A. The Linnaean System B. Cladistics and Phylogenetic Systematics The goal is to make a monophyletic classification system, in which descendants of a common ancestor are in the same taxonomic group. NEW

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview Bacteria Archaea Eukarya No nucleus no organelles peptidoglycan no no 1 RNA Poly several F-methionine Introns rare present common No histones Circular X’some Linear X’some

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview 1. Archaea “Extremeophiles” - extreme thermophiles: sulphur springs and geothermal vents - extreme halophiles: salt flats “Methanogens” Also archaeans that live in benign environments across the planet.

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview 1. Archaea 2. Bacteria - proteobacteria - Chlamydias - Spirochetes - Cyanobacteria - Gram-positive bacteria

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview 1. Archaea 2. Bacteria These groups are very diverse genetically and metabolically. Their genetic diversity is represented by the “branch lengths” of the groups, showing how different they are, genetically, from their closest relatives with whom they share a common ancestor.

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview B. Metabolic Diversity of the Prokaryotes The key thing about bacteria is their metabolic diversity. Although they didn't radiate much morphologically (spheres, rod, spirals), they DID radiate metabolically. As a group, they are the most metabolically diverse group of organisms.

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview B. Metabolic Diversity of the Prokaryotes 1. Responses to Oxygen: all eukaryotes require oxygen. bacteria show greater variability: - obligate anaerobes - die in presence of O 2 - aerotolerant - don't die, but don't use O 2 - facultative aerobes - can use O 2, but don't need it - obligate aerobes - require O 2 to live

III. The Prokaryote Domains: Eubacteria and Archaea A. Overview B. Metabolic Diversity of the Prokaryotes C. Ecological Importance - major photosynthetic contributors (with protists and plants) - the only organisms that fix nitrogen into biologically useful forms that can be absorbed by plants. - primary decomposers (with fungi) - pathogens - endosymbionts with animals, protists, and plants

Bacteria still drive major dynamics of the biosphere

The Diversity of Life I. Origin of Life Hypotheses II. Classifying Life III. The Prokaryote Domains: Bacteria and Archaea IV. The Domain Eukarya

The Diversity of Life I. A Brief History of Life II. Classifying Life III. The Prokaryote Domains: Bacteria and Archaea IV. The Domain Eukarya A. Overview: 2. 0 billion years of evolution Very diverse Unicellular, colonial, multicellular

IV. The Domain Eukarya A. Overview: - membrane bound nucleus - organelles - sexual reproduction and meiosis

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya 1. Origin of Organelles

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya 1. Origin of Organelles

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Diplomonad (Giardia) Parabasalida (Trichomonas)

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Euglenozoa Trypanosoma

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Dinoflagellates Alveolata Apicomplexans (Plasmodium) Ciliates (Paramecium)

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Stramenopiles Brown Algae Diatoms

IV. The Domain Eukarya Radiolarians A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Foraminiferans Rhizaria

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Amoebozoa

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Archaeplantae Red Algae Green Algae Plants

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Archaeplantae

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Opisthokonts

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Opisthokonts Chytrid zoospores flagella FUNGI

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Opisthokonts Choanoflagellates

IV. The Domain Eukarya A. Overview: B. Origin of the Eukarya C. Diversity of Eukarya Opisthokonts ANIMALS